Other targets included military bases and government officials, said Major Gen. Mansour al-Turki, a spokesman for the Interior Ministry.

He added that the investigation was ongoing and that it was too early to determine whether oil facilities were also targeted.

Saudi Arabia, the world’s largest oil supplier, stepped up its operations against al Qaeda in 2004 after terrorists struck an oil installation and stormed a housing complex in al-Khobar, killing 22 foreign workers.

Many al Qaeda fighters seeking to escape the crackdown fled across the border to Yemen, the source of several recent attempted bombings.

Saudi Arabia’s King Abdullah, 86, underwent surgery for a blood clot and a slipped disc in New York this week. Crown Prince Sultan bin Abdulaziz is in charge during his absence.

Saudi Arabia said its security forces broke up 19 terror cells, including one tasked with collecting money, and seized $640,000.